[The effect of phospholipid transfer protein on cigarette smoke extract induced epithelial-mesenchymal transition of rat alveolar type Ⅱ cells]

OBJECTIVE

To investigate the effect of phospholipid transfer protein(PLTP) on cigarette smoke extract(CSE) induced epithelial-mesenchymal transition(EMT) in rat alveolar Type Ⅱ cells (RLE-6TN).

METHODS

CSE of different concentrations (0%, 0.25%, 0.5% and 1%) was co-cultured for 2 or 3 days with RLE-6TN, either pre-treated or not pre-treated with siRNA-PLTP for 6 h. Expression levels of E-cadherin mRNA and Vimentin mRNA were examined by RT-PCR, while expression levels of PLTP, E-cadherin, N-cadherin and Vimentin were examined by Western blot.

RESULTS

Our results showed that the expression of E-cadherin mRNA decreased in CSE-treated groups: 1.01±0.05, 0.74±0.05, 0.65±0.03, 0.30±0.08 respectively at different concentrations of CSE (0 %, 0.25%, 0.5 %, and 1.0%); while the level of Vimentin mRNA increased significantly in 1% CSE treated cells(1.88±0.49), compared with control cells (1.01±0.20). Treatment with CSE at different concentrations (0%, 0.25%, 0.5% and 1%) showed that the protein levels of PLTP were 0.42±0.02, 0.89±0.25, 1.08±0.18, 1.61±0.06 respectively; those of E-cadherin were 1.61±0.04, 1.08±0.10, 0.62±0.08, 0.68±0.17, respectively; those of N-cadherin were 0.60±0.14, 0.57±0.26, 0.88±0.30, 1.94±0.54, respectively; and those of Vimentin were 0.61±0.05, 0.98±0.16, 1.07±0.14, 1.34±0.19, respectively; all P<0.05 when the 1% CSE group was compared with the control group. EMT induced by CSE was significantly inhibited by siRNA-PLTP.

CONCLUSION

PLTP may be involved in CSE induced EMT of rat alveolar cells.

Development and characterization of microsatellite loci in Brasenia schreberi (Cabombaceae) based on the next-generation sequencing

To understand genetic variability of the endangered aquatic herb Brasenia schreberi (Cabombaceae), we describe 31 microsatellite markers obtained using next-generation sequencing. A total of 24 individuals from the population of Jackson Lake, USA, were genotyped for each marker. Twenty-eight markers were polymorphic. The number of alleles per locus ranged from 1 to 9; the observed and expected heterozygosities ranged from 0 to 1 and from 0 to 0.751, respectively. These markers should be useful tools for genetic variation and conservation studies of B. schreberi.

Silencing NFBD1/MDC1 enhances the radiosensitivity of human nasopharyngeal cancer CNE1 cells and results in tumor growth inhibition

NFBD1 functions in cell cycle checkpoint activation and DNA repair following ionizing radiation (IR). In this study, we defined the NFBD1 as a tractable molecular target to radiosensitize nasopharyngeal carcinoma (NPC) cells. Silencing NFBD1 using lentivirus-mediated shRNA-sensitized NPC cells to radiation in a dose-dependent manner, increasing apoptotic cell death, decreasing clonogenic survival and delaying DNA damage repair. Furthermore, downregulation of NFBD1 inhibited the amplification of the IR-induced DNA damage signal, and failed to accumulate and retain DNA damage-response proteins at the DNA damage sites, which leaded to defective checkpoint activation following DNA damage. We also implicated the involvement of NFBD1 in IR-induced Rad51 and DNA-dependent protein kinase catalytic subunit foci formation. Xenografts models in nude mice showed that silencing NFBD1 significantly enhanced the antitumor activity of IR, leading to tumor growth inhibition of the combination therapy. Our studies suggested that a combination of gene therapy and radiation therapy may be an effective strategy for human NPC treatment.

Association of environmental and genetic factors and gene-environment interactions with risk of developing rheumatoid arthritis

OBJECTIVE

We developed rheumatoid arthritis (RA) risk models based on validated environmental factors (E), genetic risk scores (GRS), and gene-environment interactions (GEI) to identify factors that can improve accuracy and reclassification.

METHODS

Models including E, GRS, and GEI were developed among 317 white seropositive RA cases and 551 controls from the Nurses' Health Studies (NHS) and validated in 987 white anti-citrullinated protein antibody-positive cases and 958 controls from the Swedish Epidemiologic Investigation of Rheumatoid Arthritis (EIRA), stratified by sex. Primary analyses included age, smoking, alcohol, parity, weighted GRS using 31 non-HLA alleles and 8 HLA-DRB1 alleles, and the HLA × smoking interaction. Expanded models included reproductive, geographic, and occupational factors and additional GEI terms. Hierarchical models were compared for discriminative accuracy using the area under the receiver operating characteristic curve (AUC) and reclassification using the integrated discrimination improvement (IDI) and the continuous net reclassification improvement.

RESULTS

The mean age at RA diagnosis was 56 years in the NHS and 51 years in the EIRA. Primary models produced AUCs of 0.716 in the NHS, 0.716 in women in the EIRA, and 0.756 in men in the EIRA. Expanded models produced improvements in discrimination with AUCs of 0.738 in the NHS, 0.724 in women in the EIRA, and 0.769 in men in the EIRA. Models including genetic factors (G) or G + GEI improved reclassification over E models; the full E + G + GEI model provided the optimal predictive ability by IDI analyses.

CONCLUSION

We have developed comprehensive RA risk models incorporating E, G, and GEI that have improved the discriminative accuracy for RA. Further work developing and assessing highly specific prediction models in prospective cohorts is still needed to inform primary RA prevention trials.

Use of a multiethnic approach to identify rheumatoid- arthritis-susceptibility loci, 1p36 and 17q12

We have previously shown that rheumatoid arthritis (RA) risk alleles overlap between different ethnic groups. Here, we utilize a multiethnic approach to show that we can effectively discover RA risk alleles. Thirteen putatively associated SNPs that had not yet exceeded genome-wide significance (p < 5 × 10(-8)) in our previous RA genome-wide association study (GWAS) were analyzed in independent sample sets consisting of 4,366 cases and 17,765 controls of European, African American, and East Asian ancestry. Additionally, we conducted an overall association test across all 65,833 samples (a GWAS meta-analysis plus the replication samples). Of the 13 SNPs investigated, four were significantly below the study-wide Bonferroni corrected p value threshold (p < 0.0038) in the replication samples. Two SNPs (rs3890745 at the 1p36 locus [p = 2.3 × 10(-12)] and rs2872507 at the 17q12 locus [p = 1.7 × 10(-9)]) surpassed genome-wide significance in all 16,659 RA cases and 49,174 controls combined. We used available GWAS data to fine map these two loci in Europeans and East Asians, and we found that the same allele conferred risk in both ethnic groups. A series of bioinformatic analyses identified TNFRSF14-MMEL1 at the 1p36 locus and IKZF3-ORMDL3-GSDMB at the 17q12 locus as the genes most likely associated with RA. These findings demonstrate empirically that a multiethnic approach is an effective strategy for discovering RA risk loci, and they suggest that combining GWASs across ethnic groups represents an efficient strategy for gaining statistical power.

Characterization of 236 novel alleles at the HLA-A, -B, -C, -DRB1, -DQB1 and -DPB1 loci from China Marrow Donor Program

Two hundred and thirty-six novel human leukocyte antigen (HLA) alleles are described from volunteer donors of the China Marrow Donor Program: 71 HLA-A alleles, 79 HLA-B alleles, 43 HLA-C, 16 HLA-DRB1 alleles, 26 HLA-DQB1 and 1 HLA-DPB1. Two hundred and thirteen (90.3%) of the 236 novel alleles are single nucleotide substitution variants when compared with their most homologous allele. Seventy-eight of these single nucleotide variants are silent substitutions. The remaining novel alleles differ from their most similar allele by two to four nucleotide substitutions. Some of the novel alleles encode amino acid changes at positions not previously reported to be polymorphic, such as codons 57, 62, 67, 41 and 52 in HLA-A alleles; codons 133, 156, 201 and 215 in HLA-B alleles; codons 74, 208 and 225 in HLA-C; codons 25, 32 and 72 in HLA-DRB1; codons 20, 39 and 77 in HLA-DQB1.

The 2010 American College of Rheumatology/European League Against Rheumatism classification criteria for rheumatoid arthritis: Phase 2 methodological report

OBJECTIVE

The American College of Rheumatology and the European League Against Rheumatism have developed new classification criteria for rheumatoid arthritis (RA). The aim of Phase 2 of the development process was to achieve expert consensus on the clinical and laboratory variables that should contribute to the final criteria set.

METHODS

Twenty-four expert RA clinicians (12 from Europe and 12 from North America) participated in Phase 2. A consensus-based decision analysis approach was used to identify factors (and their relative weights) that influence the probability of "developing RA," complemented by data from the Phase 1 study. Patient case scenarios were used to identify and reach consensus on factors important in determining the probability of RA development. Decision analytic software was used to derive the relative weights for each of the factors and their categories, using choice-based conjoint analysis.

RESULTS

The expert panel agreed that the new classification criteria should be applied to individuals with undifferentiated inflammatory arthritis in whom at least 1 joint is deemed by an expert assessor to be swollen, indicating definite synovitis. In this clinical setting, they identified 4 additional criteria as being important: number of joints involved and site of involvement, serologic abnormality, acute-phase response, and duration of symptoms in the involved joints. These criteria were consistent with those identified in the Phase 1 data-driven approach.

CONCLUSION

The consensus-based, decision analysis approach used in Phase 2 complemented the Phase 1 efforts. The 4 criteria and their relative weights form the basis of the final criteria set.

Anti-citrullinated peptide antibody assays and their role in the diagnosis of rheumatoid arthritis

Increasingly, assays for the detection of anti-citrullinated peptide antibodies (ACPA) are used in RA diagnosis. This review summarizes the biologic basis and development of ACPA assays, available ACPA assays and their performance characteristics, and diagnostic properties of ACPA alone and compared to rheumatoid factor (RF) in early RA. We also review correlations, precision, costs and cost-effectiveness, availability, stability and reproducibility of the available assays. Taken together, data indicate that ACPA has a higher specificity than RF for early RA, good predictive validity, high sensitivity, apparent cost-effectiveness and good stability and reproducibility. Given its superior performance characteristics and increasing availability, ACPA is emerging as the most useful single assay for the diagnosis of RA.

Influence of hydroxyapatite crystallization temperature and concentration on stress transfer in wet-spun nanohydroxyapatite-chitosan composite fibres

Hydroxyapatite possesses appropriate osteoconductivity and biocompatibility for hard-tissue replacement implants but suffers from brittleness. One approach to overcome this problem is to incorporate nanometre hydroxyapatite (nHA) into a polymer matrix, such as chitosan, to yield a hydroxyapatite-chitosan (HC) composite. Here, a novel HC composite was synthesized and its elastic properties were investigated by varying (1) nHA concentration and (2) crystallization temperature (T), where T is a parameter which influences the morphology of the crystals. Crystals of nHA were precipitated at T = 40 degrees C and 100 degrees C, blended in a chitosan matrix, and wet-spun to yield fibres of HC composites at 5, 15, 20 and 40% concentrations (mass fraction of nHA). Scanning electron microscopy and energy-dispersive x-ray spectroscopy revealed a uniform distribution of nanocrystallites within the fibre. Tensile testing revealed that HC fibres, which comprised nHA treated at T = 100 degrees C, possessed low tensile strength, sigma(0), and stiffness, E, at low nHA concentrations but high sigma(0) and E at higher concentrations, i.e. beyond a 15% mass fraction of nHA. However, with nHA treated at T = 40 degrees C, the fibres yielded high sigma(0) and E at low nHA concentrations but low sigma(0) and E at high concentrations. The results strongly implicate the underlying effect of crystallite morphology on stress transfer at different concentrations.

Why do patients with PSP fall? Evidence for abnormal otolith responses

BACKGROUND

Patients with progressive supranuclear palsy (PSP) fall frequently, beginning early in the course of their disease. Abnormal vestibulospinal reflexes are suspected, but the angular vestibulo-ocular reflex, which is mediated by the labyrinthine semicircular canals, survives late into the course of the disease.

OBJECTIVE

To test the hypothesis that otolithic-mediated reflexes are abnormal in PSP.

METHODS

We tested otolith-ocular reflexes (the translational vestibulo-ocular reflex [tVOR]) during combined rotation-translation in nine patients with PSP and nine age-matched control subjects; subjects viewed far and near targets. We also tested click-induced otolith-spinal reflexes (vestibular-evoked myogenic potentials [VEMPs]) in 10 patients with PSP and 30 age-matched controls.

RESULTS

All patients with PSP had small tVOR responses during near viewing that were, on average, only 12% of those of control subjects (p = 0.001). Patients with PSP also showed a reduction of the amplitude of VEMPs compared to control subjects (median [range]: 54.3 [16.8 to 214] vs 149 [11.6 to 466], p = 0.001).

CONCLUSIONS

Taken together, these results indicate that abnormal otolith-mediated reflexes may be at least partly responsible for frequent falls in progressive supranuclear palsy, and deserve further study.

Novel biophysical techniques for investigating long-term cell adhesion dynamics on biomaterial surfaces

Cell adhesion on biomaterial surface is crucial for the regeneration and function of clinically viable cell and tissues. In turn, the cellular phenotypes, following the mechanochemical transduction of adherent cells on biomaterials, are directly correlated to the biophysical responses of cells. However, the lack of an integrated bio-analytical system for probing the cell-substrate interface poses significant obstacles to understanding the behavior of cells on biomaterial surface. We have developed a novel method, based on the principle of confocal reflectance interference contrast microscopy (C-RICM) that has enabled us to study the biomechanical deformation of cells on biomaterial surfaces. In this article, we would like to describe our recent development of the C-RICM system that integrates a confocal fluorescence microscope, phase contrast microscope and GFP expression system. We shall demonstrate the system by determining the adhesion contact kinetics, initial deformation rate, cytoskeleton structures of adherent cells on extracellular matrices (e.g., collagen and fibronectin) and biodegradable polymer (e.g., poly(lactic acid)) during long-term culture. We shall demonstrate that this unique approach could provide valuable biophysical information necessary for designing optimized biomaterial surfaces for cell/tissue regeneration applications.

Cholesterol deficiency in a mouse model of Smith-Lemli-Opitz syndrome reveals increased mast cell responsiveness

Mutation of the 3β-hydroxysterol Δ⁷-reductase gene (Dhcr7^−/−) results in Smith-Lemli-Opitz syndrome (SLOS). Patients, and genetically altered mice, are unable to produce cholesterol and accumulate 7-dehydrocholesterol (DHC) in serum and tissue. This causes multiple growth and developmental abnormalities as well as immune system anomalies including allergy. Because cholesterol is a key component of liquid-ordered membranes (lipid rafts) and these domains have been implicated in regulating mast cell activation, we examined whether mast cell responsiveness is altered in this model. Mast cells derived from Dhcr7^−/− mice (DHCR KO) showed constitutive cytokine production and hyper-degranulation after stimulation of the high affinity IgE receptor (FcɛRI). DHCR KO mast cells, but not wild-type mast cells, accumulated DHC in lipid rafts. DHC partially disrupted lipid raft stability and displaced Lyn kinase protein and activity from lipid rafts. This led to down-regulation of some Lyn-dependent signaling events but increased Fyn kinase activity and Akt phosphorylation. The Lyn-dependent phosphorylation of Csk-binding protein, which negatively regulates Fyn activity, was decreased. This phenotype reproduces some of the characteristics of Lyn-null mast cells, which also demonstrate hyper-degranulation. These findings provide the first evidence of lipid raft dysfunction in SLOS and may explain the observed association of allergy with SLOS.

Insulin-like growth factor-1 receptor signaling in 3T3-L1 adipocyte differentiation requires lipid rafts but not caveolae

Previously, we have found that lipid rafts/caveolae were essential for insulin-like growth factor-1 (IGF-1) receptor signaling during 3T3-L1 preadipocytes differentiation induction. However, it was not identified as to which of the membrane lipid-ordered microdomains mediates the receptor signal. Using small double-stranded RNA-mediated interference (RNAi), we successfully suppressed the caveolin-1 protein expression. In cells stably transfected with vector expressing small interfering RNA (siRNA) fragment, no caveolin-1 protein or caveola was detected. On the other hand, removal of caveolin-1 did not affect the caveolinless lipid rafts or the localization of IGF-1 receptor in lipid rafts on plasma membrane. IGF-1 receptor signal transduction and induced cellular differentiation were normal in RNAi cells with only lipid rafts. Furthermore, these IGF-1 receptor signaling events were still sensitive to the cholesterol-binding reagents. Thus, our results suggest that lipid rafts are sufficient for IGF-1 receptor signaling and the recruitment of signal molecules by caveolin-1 is not essential for IGF-1 receptor signaling.